Speckle is intensity non-uniformity, characterized as spikes and/or dips, within the output of a laser (or other light source) guided through a multimode optical waveguide, such as an optical fiber. Speckle is generally caused due to the interference between the many modes of the multimode optical waveguide.
During laser scribing of thin film materials, optical waveguides, such as an optical fiber, can be used to spatially and/or temporarily condition a laser pulse prior to being used for micromachining the thin films. However, speckle induced from such waveguides can cause significant, localized variations in laser intensity during the laser scribing. In particular, speckle induced in the final spot of the laser scribing can result in significant variations in the micromachined or scribed thin films. Thus, speckle can lead to depth variations of the laser scribe in the thin films.
As such, a need exists for reducing the influence of speckle on a laser spot delivered through an optical wave guide, particularly in the field of laser scribing thin films (e.g., in the formation of photovoltaic modules).